There are numerous situations where it is necessary or desirable to deliver a flow of breathing gas non-invasively to the airway of a patient, i.e., without intubating the patient or surgically inserting a tracheal tube in their esophagus. For example, it is known to ventilate a patient using a technique known as non-invasive ventilation. It is also known to deliver continuous positive airway pressure (CPAP) or variable airway pressure, such as a bi-level pressure that varies with the patient's respiratory cycle or an auto-titrating pressure that varies with the monitored condition of the patient. Typical pressure support therapies are provided to treat a medical disorder, such as sleep apnea syndrome, in particular, obstructive sleep apnea (OSA), Cheyne-Stokes respiration, or congestive heart failure.
Non-invasive ventilation and pressure support therapies involve the placement of a patient interface, which is typically a nasal, nasal/oral mask, or a total face mask, on the face of a patient. The patient interface couples the ventilator or pressure support system with the airway of the patient, so that a flow of breathing gas can be delivered from the flow/pressure generating device to the airway of the patient.
Because patient interfaces are typically worn for an extended period of time, a variety of concerns must be taken into consideration. For example, in providing CPAP to treat OSA, the patient normally wears the patient interface all night long while he or she sleeps. One concern in such a situation is that the patient interface is as comfortable as possible, otherwise the patient may avoid wearing the interface device, defeating the purpose of the prescribed pressure support therapy. It is also important that the patient interface provide an adequate seal against the patient's face without discomfort. One problem that can arise is that in order for the mask to maintain a seal without any undue gas leaks around the periphery of the mask, the mask is often compressed against the patient's face with too much force, causing discomfort.
Typically, patient interfaces include a member housing shell and a cushion (also referred to as a seal or seal member) attached to the shell. The cushion contacts the surface of the patient and operates to both locate and seal the interface with the face of the patient. The member is held in place by a headgear assembly that wraps around the head of the patient. Together, the patient interface and headgear form a patient interface assembly. A typical headgear assembly includes flexible, adjustable straps that extend from the patient interface to attach the patient interface to the patient.
In addition to the patient interface described above, it is also known to have patient interfaces with nasal pillows that seal within the nares of a patient. As best appreciated with reference to FIG. 1, the nasal pillows associated with a tubular air delivery system were worn with semi-rigid or rigid headgear 102 attached to the crown of the head. More specifically, as shown in FIG. 1, prior art nasal pillows 104 are supported by a shell 106 which, in turn, is connected to a swivel 108 which, in turn, is coupled to an over-the-head hose 110 which is connected to a gas source 112. Headgear 102 attached to the crown of a patient's head secures the assembly in position to enable the delivery of a suitable breathing gas to, and from, the patient via the nasal pillows. In an alternative (not shown) to the arrangement in FIG. 1, a flexible tube strapped to the face or around the ears of the patient may replace the over-the-head hose.
Although nasal pillows have performed very well in the art, further advancements would be desirable. For instance, contemporary nasal pillows are often compressed within the nares of the patient's nose in order to form an adequate seal and properly locate the pillows on the face of the patient. In addition, it is often necessary to utilize a rather large and bulky headgear assembly to properly support and locate the patient interface. As best appreciated with reference to FIG. 1, the nasal pillows extend upward in a hook-like configuration. This configuration tends to pry the patient's nose upward which may result in discomfort for some patients. Secondly, one of the strengths of this device is that it minimized the degree of contact with the patient's face; yet, this also presents a drawback since the prying force is concentrated in a small region. Furthermore, properly orienting the device in order to affect an adequate seal may require making multiple adjustments to the headgear assembly. In addition, nasal pillows may lack the stability needed which could ultimately result in compromising the seal between the patient and the nasal pillows.
What is therefore needed, and not disclosed in the prior art, is an improved patient interface that includes nasal pillows.